Displays, posters, signs, display cards, placards, and the like, are used extensively for advertising purposes. Displays of this type bear a picture, characters, figures, letters, or a combination thereof, printed on a paper sheet or web. These displays typically are large, and frequently are exhibited as reflective art from a wall hanging or window hanging, and as such are to be viewed from the front side only, that is, by reflected light. When a display of this type is illuminated from behind but viewed from the front, that is, viewed by transmitted light, such as in the case of a window hanging, the colors of the printed subject matter or image area appear washed out or faded, or less intense or less vivid, relative to the same display viewed by reflective light only.
Displays have been used in combination with a light box. In such an arrangement, the display is set for viewing by positioning or suspending the display in the frame of a light box, which comprises a closed box with an open front where the display is suspended, and a light source is disposed to the rear of the display for viewing by transmitted light. More recently, displays for a light box have been printed on plastic, which have been commercially successful but nonetheless have several drawbacks or objectionable features, as discussed hereinbelow in greater detail. The display sheet, whether of paper, plastic, or a combination thereof, is sufficiently opaque so that the image area is visible in daylight when viewed by reflected light, but yet thin enough, or of sufficient translucency, to be viewed by transmitted light. Thus, when the display is illuminated by the light transmitted from behind, it is intended that the print area or image area be sufficiently clear to the viewer from the front side, but that the purpose of the transmitted light is to enhance the colors, thereby rendering the image area aesthetically pleasing to the viewer. However, paper displays for viewing from a light box with transmitted light appear washed out or faded, as stated above in the case of a window hanging, and therefore have achieved very little or no commercial success. Plastic displays for this purpose are aesthetically pleasing when viewed with transmitted light, but if viewed by reflective light only, the print area appears dark or dull and there is a loss of detail, as discussed below.
The prior art shows advertising posters adapted for alternative viewing by reflected light and by transmitted light. In U.S. Pat. No. 1,487,705 discloses a first picture visible by reflected light, and a second identical picture on transparent photographic film placed coincident with the first, thereby enhancing the contrast when viewing the picture by transmitted light. A composite of two pictures, not identical, and registering as to all parts, is shown in U.S. Pat. No. Re. 15,454. A certain representation of the picture is visible when viewed by reflected light from the front, and a combined representation is visible when viewed by transmitted light.
A composite sign or display card for viewing from both sides is disclosed in U.S. Pat. No. 1,781,283. According to this patent, the poster or sign is partly opaque, and advertising data is printed on both sides, but each side is visible from one side only. Another portion of the poster is of a translucent material, and the printing is visible from both sides. Printing on the translucent portion can be a double print, that is, the printed matter is duplicated on the opposite side of the sheet in reversed form and registering with the print on the outer face. The sign was expressly designed as a window sign, which means that the lights source is variable and nonspecific, and because the sign is not matched in its entirety, the sign is for viewing from both sides. Similar prints for window shades for viewing from both sides is taught in U.S. Pat. No. 366,449, wherein it states that the prior art teaches providing opposite faces of a window shade with the same designs in register.
A vivid color contrast is achieved by the invention disclosed in U.S. Pat. No. 4,716,672, wherein a laminate is formed comprising a transparent sheet, the visible image, and aluminum foil In U.S. Pat. No. 4,666,757, the image is printed to the underside of a transparent sheet, and affixed to a coextensive, opaque backing sheet, thereby providing a bright and vivid color print protected from smudges or abrasion. In U.S. Pat. No. 2,096,180, two individual pictures are printed on opposite sides of a sheet, and an opaque layer is interposed between the two images, whereby one image is visible from one side and the other from the opposite side.
Plastic posters for viewing from the front with transmitted light from behind are currently in extensive use. The image area on the plastic sheet or substrate is produced in halftone to create an illusion of shading or tonal value, as described hereinbelow in greater detail. The plastic poster bears a right reading or image on the front side, and in some instances is also printed on the back side with a reverse image. When viewed with transmitted light, a highly visible sign is seen by the viewer, and if there is printing of a reverse image on the back side, the colors are intensified, thereby rendering a more aesthetic or pleasing picture. A poster of this type is known in the art as "translite," and as used herein and in the appended claims, the term "translite" is intended to include a sufficiently translucent substrate (e.g., sheet) on which a photographic image has been reproduced onto the substrate by printing means for display and lit from behind to permit a clear front view. Plastic sheets composed of polystyrene and polycarbonate have been commonly employed for printed translites. Also, it should be understood that such terms as display, poster, sign, bill, graphic board, display card, placard, and similar terms, are used synonymously and interchangeably, and such use is intended to mean that type of sheet or web bearing printed matter or image.
Plastic substrates or sheets such as used for translites have numerous disadvantages or objectionable features. Chief among these disadvantages is costs. Plastic materials are relatively expensive. Further, the plastic materials such as polystyrenes tend to be brittle, and therefore must be provided as a sufficiently thin sheet to be flexible, yet be thick enough to have sufficient strength. Printing on a plastic surface requires special handling and special inks, thereby substantially increasing the costs, and such inks or the components thereof have the potential of causing health and/or environmental problems. It also is highly significant that, although plastic translites intensify the colors used for the image area, this effect is limited to transmitted light only, because of the inherent qualities of the plastic and because of the required thickness of the substrate. Thus, when a plastic translite is viewed by reflective light only, the print area appears dark or dim, manifesting a loss of brilliance and detail, and therefore is not aesthetically pleasing.
This invention has therefore as its purpose to provide a new and useful paper translite that is aesthetically pleasing when viewed by reflective light and by transmitted light, thereby overcoming the disadvantages of the prior art, and further providing such a backlit display that is environmentally beneficial in that a portion or all is substantially biodegradable.